Chapter 2. Objectives

Transcription

1 Chapter 2 A Systems View and Systems Methodology Objectives Define the systems approach and its impact on project management Define a PMLC and understand how to apply it Define several SDLC models and know when to use each different type Define the relationship between the PMLC and the SDLC and understand how the two work together

2 Systems View or Systems Thinking Approach

3 A System and Its Characteristics A System is an inter-related set of components, with an identifiable boundary, working together for some purpose. Any system has nine (9) characteristics: 1) Components - an irreducible part or aggregation of parts 2) Relations (links) - dependence of one subsystem on one or more subsystems 3) A Boundary - a line that sets off the system from its environment 4) A Purpose - the overall goal or function of a system 5) An Environment - everything external to a system that interacts with the system 6) Interfaces - points of system-environment and subsystemsubsystem contacts 7) Input - whatever a system takes from its environment 8) Output - whatever a system returns to its environment 9) Constraint(s) - limit(s) to what a system can accomplish A General Depiction of a System Source: Management Information Systems, 8 th Ed., K. Landon and M. Landon

4 System s Boundary and Environment A system Most of what a Project Manager does exists on the boundaries! This is one more reason that PM must have multiple skills: 1) analytical (problem solving), 2) technical, 3) managerial, 4) communication. CIS Project Management (as a process) Life Cycle (CIS PM LC)

5 PM LC SW/IT/CIS PM Life Cycle A SW/CIS project management life cycle is a prescribed order of phases (smaller segments of the entire project) in which each contains a specific deliverable which collectively deliver a result. What work (tasks) will (should) be done in each phase. A definition of each phase s deliverables and when. The change control process for each deliverable What resources are involved in each deliverable Criteria that needs to be met complete each phase SW/CIS Devel. Model 5 SE framework activities (for large SW projects, or in large-size companies). But in what order? returns/iterations/loops? Feedback from users? Construction Modeling Communication Deployment Planning

6 Classic Models (multiple details in CS590 course) Main Types of SW/IT/CIS Development Process Flow (various types will have significant impact on project time, cost, human resources, quality, etc.) a) Linear process flow ( no feedback, no iterations/loops) b) Iterative process flow ( a circular manner, with a feedback, with iterations) c) Evolutionary process flow (with various versions or increments released) d) Parallel process flow ( no feedback, no iterations/loops, with parallel activities) Software team (project manager, system analyst, software engineers, etc.) MUST identify the best (optimal) process flow or, possibly, a combination of them for a specific software project.

7 Question: Why do we need to know all those types of SE Process Flow? Answer: It is about Money, Time, People, and Quality. Waterfall Model Strengths Is well understood by most practitioners Easier to manage than the new agile methods When working on large complex applications When teams are distributed geographically When using a less experienced IT resources Weaknesses Does not accommodate a change to requirements very well All Requirements must be known and defined in the beginning Does not allow a repeat of a phase (iterate) Limited adaptability to different project types Encourages communications gap between users and IT

8 Evolutionary Prototyping Model Focuses on gathering correct and consistent requirements and is the approach of building a system incrementally through a series of gradual refinements or prototypes Requirements are discovered throughout the process and the system is repeatedly refined based on those discoveries Allows developers to learn from each prototype and apply those lessons to future versions The prototyping approach is an excellent choice for research and development projects, quickly building mockups of system components for user review allows for timely feedback that can be incorporated in the next design or prototype Strengths Visibility customers see steady progress Useful when requirements are changing rapidly or no one fully understands the requirements Weaknesses It is impossible to know at the beginning of the project how long it will take There is no way to know the number of iterations/phases that will be required Difficult to build an accurate cost estimate Spiral Model Similar to the classic waterfall model with the addition of risk analysis and iterations Emphasizes the need to go back and reiterate earlier stages a number of times as the project progresses It's actually a series of short waterfall cycles, each producing an early prototype representing a part of the entire project Examples: 1) Win 95, Win 98, Win 2000, Win XP (2002), Win Vista, Win 7, Win 8, etc. 2) Oracle DB 8, 9, 10, 11, etc. Strengths Good for large complex projects Accommodates change well Can react to risks very quickly Software produced early in the life of the project Increased user visibility Weaknesses Can be a costly model to use Risk analysis requires highly specific expertise Project s success highly dependent on risk analysis Doesn t work well for small projects

9 Spiral Model versus Incremental Model Iterative Model

10 C o m m u n i c a t i o n P l a n n i n g M o d e l i n g analysis design C o m m u n i c a t i o n C o n s t ru c t i o n code t es t P l a n n i n g D e p l o y m e n t d e l i v e r y f e e d b a c k M o d e l i n g anal ysis design C o n s t r u c t i o n code t est C o m m u n i c a t i o n D e p l o y m e n t d e l i v e r y f e e d b a c k P l a n n i n g M o d e l i n g analysis design Co n s t r u c t i o n code t es t D e p l o y m e n t d e l i v e r y f e e d b a c k Incremental Model increment # n increment # 2 delivery of nth increment increment # 1 delivery of 2nd increment delivery of 1st increment project calendar time The 1 st increment = a core product. Following increments are aimed to better meet customer requirements and deliver additional functionality Source: Software Engineering, 7 th Ed., by Roger Pressman The Incremental Model: Real World Example (linux operating system)

11 Iterative and Incremental Model Repeating a process phase until ultimately meeting the project requirements (iterating the phases) and developing and delivering a system in stages (increments) The system grows by adding new and enhanced functionality with each build cycle Each cycle tackles a relatively small set of requirements and proceeds until the entire scope of the project is completed Strengths Generates working software quickly and early Flexibility Ease of testing Ease of risk management Weaknesses Not easy to manage Must be able to estimate well to plan iterations Hard to determine cost and time estimates early in the process New Models for product development life cycle (based on ideas of agility, agile programming)

12 Scrum Model With possible change of requirements, time frame, resources, technology, etc. Based on the concept that software development is not a defined process, but an empirical process with complex input to output transformations that may or may not be repeated under differing circumstances The main idea of Scrum is that systems development involves several environmental and technical variables that are likely to change during the process (for example, requirements, time frame, resources, technology) The name Scrum is essentially derived from the game of rugby. In rugby, a play where two opposing teams attempt to move against each other in large, brute-force groups is called a scrum. Each group must be quick to counter the other s thrust and adjust and exploit any perceived weakness, without the luxury of long term planning This makes the development process unpredictable and complex, requiring flexibility of the systems development process in order to respond to these changes Scrum Model Strengths SCRUM Model strengths: The project is more manageable Progress is made, even when requirements are not stable Everything is visible to everyone Team communication improves The team shares successes along the way and at the end Customers see on-time delivery of increments Customers obtain frequent feedback on how the product actually works SCRUM Model weaknesses: Doesn t work well with large teams Requires experienced developers Not good for mission or life critical systems. Requires hands-on management, but not micromanagement Requires constant monitoring both quantitatively and qualitatively

13 Integration of Project Management Life Cycle and Software Development Life Cycle

14 Systems View in Action: 1) Development (make by yourself) is NOT the only option for Project manager. 2) PM must consider other options Reuse, Buy, Contract, etc., and find the optimal project solution (cost M, time M, HR M., etc.) Chapter 2 A Systems View and Systems Methodology (additional information)

15 Rational Unified Process (RUP) Model Developed as a process complement to the Unified Modeling Language (UML) Adaptable process framework which can be used for both heavy and light projects Based on iterative development paradigm with Four Phases Inception, Elaboration, Construction and Transition Each phase contains one or more iterations Rational Unified Process (RUP) Model: Strengths and Weaknesses RUP Strengths Risks are mitigated (diminished) earlier Change is more manageable Higher level of reuse The project team can learn along the way Better overall quality Enhances team productivity, by providing every team member with easy access to a knowledge base with guidelines, templates and tool mentors for all critical development activities. RUP Weaknesses Not easy to tailor to smaller projects Has a large volume of process guidelines and is detail heavy

16 extreme Programming (XP) Basic approach includes short development cycles, frequent updates, dividing business and technical priorities, and assigning user stories Four key values: communication, feedback, simplicity, and courage Designed to allow small development teams to deliver quickly, change quickly, and change often XP Strengths The project is more manageable Progress is made, even when requirements are not stable Everything is visible to everyone Team communication improves The team shares successes along the way and at the end Customers see on-time delivery of increments Customers obtain frequent feedback on how the product actually works XP Weaknesses Doesn t work well with large teams/projects Requires very experienced team members

17 Integration PROJECT Life Cycle (Phases) and PRODUCT Life Cycles The project life cycle applies to all projects, regardless of the products being produced Product life cycle models vary considerably based on the nature of the product Most large software products are developed as a series of projects (or, a Program) Project management is conducted during all of the product life cycle phases Integration Project to Product Life Cycles 1) The overlap occurs from project life cycle to product life cycle during Analysis and Design. 2) During project Execution the bulk of the product is built.

18 Integration of Project to Product Life Cycles Multiple Phases/Projects (like nested loops in programming)